1. Technical Field
Example embodiments of the present invention relates in general to a digital rights management (DRM) and more specifically to methods and apparatuses for providing DRM interoperability.
2. Description of the Related Art
Development of a digital distribution technology enables users to more easily enjoy various contents. However, as the number of users who illegally use contents has increased, a digital rights management (hereinafter, “DRM”) has been introduced to prevent illegal copy and to distribute contents safely and transparently. However, existing DRM techniques do not guarantee interoperability between content providers since content providers employ different DRM techniques. This causes a problem in that users have to purchase a single content several times to use it in different devices.
FIG. 1 is a concept diagram for explaining a problem occurring in an environment in which a plurality of DRM service providers and a specific DRM supporting device are present. The same content may be encrypted by a plurality of different DRM techniques and distributed in a content market. It is understood from FIG. 1 that the same content is encrypted by techniques of a DRMownerand a DRMdesire which are different DRM service providers and distributed. However a content replay device having a limited resource and performance is difficult to support all kinds of DRM techniques which are shown on the content market. That is, a device which supports only a specific DRM technique can replay only a content which is encrypted by a specific DRM technique. Therefore, as illustrated in FIG. 1, a device which supports the DRMowner cannot replay a content which is encrypted by a DRMdesire technique.
FIG. 2 is a concept diagram for explaining a problem occurring in an environment in which a plurality of DRM service providers and a plurality of specific DRM supporting devices. Typically, a user downloads a content to his/her personal computer (PC), transmits the content to a portable or handheld device such as an MP3 player, a portable media player (PMP), a personal digital assistant (PDA), and replays the content in the portable device. Referring to FIG. 2, for example, when the user has purchased a content encrypted by the DRMowner technique from the DRMowner and has stored the content in his/her PC, in order to replay a device which supports the DRMdesire technique, the user has to purchase a content encrypted by the DRMdesire technique from the DRMdesire.
In order to resolve the problems, a transmission interface standardization technique has been suggested. A content is transmitted between devices according to a standard format which is previously agreed. Export/Import (EXIM) and Intellectual Property Management and Protection (IPMP) are representative techniques and have a merit that interference of an external DRM element is not needed and each DRM service provider does not need to open her own security element to a third party. Generally, the DRM service provider desires to trace a sold content in order to pursue a profit and to be given compensation for it, while according to the transmission interface standardization technique, a license is modified inside a device before transmitted. Therefore, there is a problem in that the DRM service provider cannot trace a content with high reliability and cannot be guaranteed a profit.
As another resolution, a technique using an intermediary has been suggested. The intermediary has already known security elements of all DRMs and converts a content and a license according to respective DRM formats between devices using the security elements. This technique has an advantage that existing DRM-related devices do not need to be modified but has a disadvantage that the intermediary has to know all security elements. Similarly to the transmission interface standardization technique, the DRM service provider cannot trace whether or not her content is used with high reliability and cannot be guaranteed a profit.
The above-mentioned techniques are under the assumption that DRM security elements, that is, an encryption method and a content format, are opened or standardized when a content is transmitted. However, since a problem in that the DRM service provider cannot be guaranteed a profit and an additional security problem which will occur due to interoperability support cannot be resolved, the techniques are difficult to be adopted.